In mobile communication, a signal is sent from a base station to user equipment by using a physical antenna on a base station side. For deployment of a macro network, in order to improve a system capacity and increase coverage of a base station, generally, a directional antenna technology rather than an omnidirectional antenna technology is widely used for an antenna of the base station of the macro network in a wireless communications system. A diagram showing that a gain of a directional antenna changes as a horizontal direction or a vertical direction changes is referred to as a gain directivity diagram. Antennas of base stations can be classified into passive antennas and active antennas. A gain directivity diagram of an active antenna can change in real time, that is, a high-gain direction of an active antenna can be adjusted in real time to an area where there are a relatively large quantity of services, so as to increase a system throughput.
An important application solution of an active antenna system is cell splitting. The so-called cell splitting refers to splitting a cell in the active antenna system into two or more cells. Generally, cell splitting is implemented by replacing a relatively wide beam with multiple narrower beams. Splitting a cell in a horizontal direction is referred to as horizontal splitting, and splitting a cell in a vertical direction is referred to as vertical splitting. After cell splitting, one original cell is split into two or more cells, and the cells obtained after splitting use a same physical resource such as time, frequency, and a code word, which helps increase a system throughput. Because one beam in one original cell is split into multiple beams in multiple cells and the multiple beams multiplex a same physical resource, interference exists between the multiple beams, and a direct result of cell splitting is an increase in cell interference intensity. If a beam design used for cell splitting is not optimized, the system throughput is greatly reduced due to the interference problem.